1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to an apparatus for fabricating a liquid crystal display device and a method of fabricating a liquid crystal display device.
2. Description of the Related Art
In general, a process of fabricating a liquid crystal display (LCD) device includes a substrate fabrication process, a cell fabrication process, and a module process. During the substrate fabrication process, a plurality of thin film transistors (TFTs) are fabricated onto a cleaned glass substrate during TFT fabrication processes, and a color filter is fabricated onto a cleaned glass substrate during color filter fabrication processes. During the TFT fabrication processes, the plurality of TFTs and a plurality of pixel electrodes are fabricated on a first substrate. During the color filter fabrication processes, red, green, and blue color filter layers are formed using a dye or pigment, and a common electrode (ITO) is formed on a second substrate upon which a black matrix is formed.
During the cell fabrication process, liquid crystal material is injected between a first substrate and a second substrate, thereby forming an LCD cell panel. Accordingly, the first substrate is provided with the TFTs and the pixel electrodes, and the second substrate is provided with the color filters and the common electrode. Thus, the first substrate and the second substrate are attached to each other with a space therebetween, and the liquid crystal material in injected into the space.
During the module process, a circuit section for processing signals is fabricated, and a module is fabricated by connecting the LCD cell panel with the signal processing circuit section.
The cell fabrication process requires processes for performing grounding to generate a voltage difference between the two substrates according to the electric signals, as well as processes for attaching the first substrate and the second substrate together. These processes are achieved by connecting the common electrode of the second substrate to the first substrate.
The method of manufacturing an LCD according to related art will now be described.
FIG. 1 is a plan view of an LCD panel according to the related art, and FIG. 2 is a cross sectional view along I-I′ of FIG. 1 according to the related art. In FIG. 1, an LCD device includes a first substrate 1, a second substrate 2, an active region 12, a sealant 7, and silver pastes 8. The active region 12 includes a plurality of pixel regions 6, which are defined by a plurality of gate lines 3 and a plurality of data lines 5 arranged in a matrix configuration on the first substrate 1. In order to protect the liquid crystal material (not shown) within the active region 12 from damage, the sealant 7 surrounds edges of the active region 12, thereby attaching the first substrate 1 to the second substrate 2. In addition, the silver (Ag) pastes 8 are formed outside the sealant 7. The silver pastes 8 are spaced from each other, and electrically ground the first substrate 1 and the second substrate 2 using silver particles in the silver pastes 8 as a conductive material. The silver pastes 8 include two or more silver pastes formed on the first and second substrates 1 and 2. For example, when the first and second substrates 1 and 2 are small-sized, two silver pastes 8 may be formed at top and bottom corners of the first and second substrates 1 and 2.
In FIG. 2, the LCD device includes a first substrate 1, gate lines (not shown), a gate insulating film 9, a semiconductor layer 10, thin film transistors (not shown), a passivation film 15, pixel electrodes 16, and a first alignment film 17a. Each of the gate lines (not shown) include a gate electrode 4 extending therefrom, and are formed along an inner surface of the first substrate 1. In addition, the gate lines (not shown) are arranged in rows along the inner surface of the first substrate 1, and the gate insulating film 9 is formed along an entire surface of the first substrate 1. The semiconductor layer 10 is formed having an island shape on the gate insulating film 9 at an upper side of the gate electrode 4.
Then, a source electrode 13a and a drain electrode 13b are formed on the semiconductor layer 10, thereby completing the thin film transistor (not shown). Next, the passivation film 15 is formed along the entire surface of the first substrate 1 including the source electrode 13a and the drain electrode 13b. Then, the pixel electrodes 16 are formed on the passivation film 15, and are connected to the drain electrodes 13b. Accordingly, the first alignment film 17a aligns liquid crystal molecules of a liquid crystal material (not shown) disposed between the first and second substrates 1 and 2.
In FIG. 2, the second substrate 2 includes a black matrix 18, a color filter layer 19, a common electrode 21, and a second alignment film 17b. The black matrix 18 is formed along an inner surface of the second substrate 2, and blocks light corresponding to the gate lines 3, the data lines 5, and the thin film transistor (not shown). The color filter layer 19 produces colored light at portions corresponding to the pixel electrodes 16. Then, the common electrode 21 is formed on the black matrix 18 and the color filter layer 19, and generates a voltage difference between the common electrode 21 and the pixel electrode 16 of the first substrate 1. Next, the second alignment film 17b is formed on the common electrode 21 and aligns the liquid crystal molecules of the liquid crystal material (not shown) disposed between the first and second substrates 1 and 2.
The LCD device further includes the liquid crystal material (not shown), spacers 22, a sealant 7, and silver pastes 8. The liquid crystal molecules are aligned by the first and second alignment films 17a and 17b between the first substrate 1 and the second substrate 2, and the spacers 22 are made of plastic material and maintain the space between the first substrate 1 and the second substrate 2. In order to prevent moisture and foreign material from being introduced into the liquid crystal material, the sealant 7 is attached to the edges of the active region 12, as shown in FIG. 1, of the first and second substrates 1 and 2, thereby sealing the active region 12. The silver pastes 8 electrically connect the common electrode to the first substrate at an exterior portion of the sealant 7.
A method of fabricating the above-described LCD panel includes performing a TFT array process on the first substrate 1 and performing a pixel electrode process on the second substrates 2. Then, the spacers 22 are dispersed onto one of the first or second substrates 1 or 2 to maintain a uniform interval between the first substrate 1 and the second substrate 2. Next, the sealant 7, such as thermosetting resin or epoxy resin hardened by ultraviolet, is printed at edges of the active region 12 of the first and second substrates 1 and 2. Then, the silver pastes 8 are formed to connect the common electrode of the second substrate 2, wherein the silver pastes 8 can be formed using a print method including a screen mask or using a dotting method including a dispenser.
During the print method, the screen mask is placed on the second substrate 2 and the silver pastes are printed onto the second substrate 2 including the screen mask. This method is disadvantageous since significant amounts of the silver pastes is wasted.
During the dotting method, the silver pastes are individually formed one-by-one so that the silver pastes 8 may be formed at desired positions using proper amounts of silver.
FIG. 3 is a plan view of a dotting method for fabricating an LCD device according to the related art. In FIG. 3, an LCD device includes a first substrate 1, a plurality of LCD cells 25 formed on the first substrate 1, a sealant 7 surrounding edges of an active region 12 within the LCD cell 25, and silver pastes 8 dotted at an exterior portion of the sealant 7.
A dispenser 24 is used to dot the silver pastes 8 at the desired positions of the first substrate 1 using an extrusion process that includes application of a predetermined pneumatic pressure from a controller (not shown).
During the cell fabrication process, the silver pastes 8 should be formed with a predetermined size and at predetermined interval distances between each of the silver pastes 8 around the sealant 7 of the LCD cell of the second substrate 2 to enhance productivity. However, during the process of dotting the silver pastes, since the controllers for providing pneumatic pressure correspond to the dispensers 24 in a one-to-one relationship, the dispenser 24 should move many times so as to dot the plurality of silver pastes 8 for each of the individual LCD cells. In other words, significant amounts of tacking time is required to manufacture the LCD device.